<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>选择器</title>
	<style>
		/*span{
			color: red;
			font-size: 50px;
		}*/

		#xiaoming{
			color: red;
			font-size: 50px;
		}

		.title{
			color: blue;
			font-size: 40px;
		}

		#box span{
			color: green;
		}

		span,i,b{
			font-size: 100px;
		}

		*{
			color: red;
		}

		p span{

		}
		
	</style>
</head>
<body>
	<span id="header_nav">我是span1</span>
	<span class="title">我是span2</span>
	<span class="title">我是span3</span>
	<p>
		<a href="">
			<span>我是span4</span>
		</a>
		<span>我是span4</span>
	</p>
	<p id="box">
		<span>我是span44</span>
	</p>
	<span>我是span5</span>
	<span>我是span6</span>
	<span>我是span7</span>
	<span>我是span8</span>
	<i>我是i</i>
	<b>我是b</b>
</body>
</html>